What is linear regression?

Linear regression fits this model to your data:

The slope quantifies the steepness of the line. It equals the change in Y for each unit change in X. It is expressed in the units of the Y axis divided by the units of the X axis. If the slope is positive, Y increases as X increases. If the slope is negative, Y decreases as X increases.

The Y intercept is the Y value of the line when X equals zero. It defines the elevation of the line.

Correlation and linear regression are not the same. Review the differences.

Simple vs. multiple linear regression

Simple linear regression is shown above. There is only a single X variable. In contrast, multiple linear regression defines Y as a function that includes several X variables.